The present invention relates generally to sewing machines of a type which sews an elongated sewing material, such as a tape or cord, onto a sewing workpiece, such as a fabric, through lock stitching.
Heretofore, there have been known sewing machines of a type which includes a vertically driven needle bar, a sewing needle fixed to the lower end of the needle bar, a rotary member mounted concentrically with the needle bar and freely rotatable about the axis of the needle bar, and a guide fixed to the rotary member for guiding an elongated sewing material to a needle drop position of the sewing needle. The sewing machines of this type operate to sew the sewing material onto a sewing workpiece (fabric) through lock stitching while controlling the rotation of the rotary member in accordance with a moving direction of the fabric based on embroidery data and appropriately adjusting the orientation of the guide to optimize the direction in which the sewing material is guided to the needle drop position of the sewing needle.
When sewing the sewing material on the sewing machines of this type, there is a need to pull out in advance a certain length of the sewing material from the guide so that the sewing material can be reliably sewn at a predetermined sewing start position or point of the sewing material. Therefore, it has been customary for a human operator to pull out in advance a certain length of the sewing material from the guide so that sewing is started at a portion of the sewing material following the pulled-out portion. Upon completion of sewing of the sewing material, the human operator cuts the sewing material near a sewing end position or point of the sewing material, but also cuts off, prior to the start of next sewing, the relatively long previously-pulled-out portion preceding the sewing start point.
Some of the conventionally-known sewing machines of the aforementioned type are provided with a cutter device for cutting the sewing material with a view to reducing a burden on the human operator cutting the sewing material. International Patent Application Publication WO 2007-128364 (hereinafter referred to as “patent literature 1”), for example, discloses a sewing machine which includes a sewing-material cutter device vertically movable relative to the rotary member and rotatable about the axis of the needle bar together with the rotary member. The sewing machine also includes a presser foot member vertically movable, in synchronism with vertical movement of the needle bar, for pressing the sewing workpiece (fabric) from above as the presser foot member descends. Upon completion of sewing, the presser foot member evacuates upwardly to an evacuation position. The cutter device ascends or descends in interlocked relation to the descending or ascending movement of the presser foot member. Namely, the cutter device descends once the presser foot member ascends to the evacuation position, and ascends once the presser foot member descends to from the upper evacuated poison to its predetermined sewing operating position.
The cutter device includes a cutting blade that pivots in response to the ascending or descending movement of the cutter device, and a fixed blade that cuts the sewing material in conjunction with the cutting blade. As the cutter device descends, the cutting blade pivots away from the fixed blade. As the cutter device ascends, the cutting blade pivots toward the fixed blade to cut the sewing material in conjunction with the fixed blade.
When the sewing material is to be cut, the presser foot member is first moved to the evacuation position. Thus, the cutter device descends, in response to which the cutting blade pivots away from the fixed blade. Then, the sewing material (fabric) is moved and the cutter device is caused to rotate about the axis of the needle bar so that the sewing material is positioned between the cutting blade and the fixed blade. After that, the presser foot member is lowered to the predetermined sewing operating position, upon which the cutting blade is caused to pivot toward the fixed blade, in response to the ascending movement of the cutter device, so that the sewing material is cut near its sewing end point.
With the cutter device disclosed in patent literature 1, the sewing material is cut near its sewing end point, i.e. at the needle drop position, and thus, the human operator has to pull out a certain length of the sewing material from the guide member before resuming or restarting the sewing operation after the cutting of the sewing material. Such operation tends to be extremely cumbersome (requiring time and labor) particularly in a case where the sewing machine is a multi-head sewing machine.
Japanese Patent Application Laid-open Publication No. 2007-68829 (hereinafter referred to as “patent literature 2”) discloses a sewing machine where a sewing-material cutter device is provided in a position remote from the needle drop position in order to avoid the aforementioned inconvenience. The cutter device disclosed in patent literature 2 is constructed to be movable between an evacuation position where the cutter device does not impede the sewing operation and a cutting position where it can cut the sewing material, and it includes a catching or hook portion for catching the sewing material as the cutter device moves from the evacuation position to the cutting position, a fixed blade, and a cutting blade movable in interlocked relation to further movement of the cutter device after the sewing material is caught by the catching portion.
When the sewing material is to be cut, the sewing workpiece (fabric) is moved so that the sewing end point of the swing material is moved close to the cutter device. Then, the cutter device is moved from the evacuation position to the cutting position so that the sewing material is caught by the catching portion. Then, the cutter device is moved to a further cutting position, in response to which the cutting blade cuts the sewing material near the sewing end point through cooperation between the cutting blade and the fixed blade. Because the sewing material (fabric) is moved as above when it is to be cut, it is pulled out from the guide member by a length corresponding to a moved amount of the sewing material. Thus, the human operator does not pull out the sewing material from the guide member when resuming the sewing operation, which can reduce the burden on the human operator.
However, with the conventional techniques represented by patent literature 1 and patent literature 2, there is a need for a human operator to cut off, after completion of the sewing, the portion (i.e., portion preceding a sewing start point) of the sewing material having been pulled out in advance from the guide prior to the sewing. Namely, with the conventional techniques, time and labor are required for, after completion of the sewing, cutting the portion (i.e., portion preceding the sewing start point) of the sewing material having been pulled out in advance from the guide prior to the sewing. Also, such a portion or length of the sewing material having been pulled out in advance, i.e. a length necessary for reliably sewing a sewing start portion, would undesirably become a waste of the sewing material.